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Drontheim Custom Shop – Reproduction A1 HBAR Rifle (Colt Mod. 606)

Drontheim Build Works


This build is a reproduction of a classic Colt A1 Model 606 HBAR Rifle.


A1 Upper Receiver


  • Platform: AR15
  • Profile: Original slick-side A1 carry handle, no shell deflector
  • A1 sights
  • Material: 7075-T6 forged aluminum
  • Feed Ramps: standard ramps
  • Finish: Mil-spec Type III Hard Anodized
  • .250 takedown pin holes
  • Includes port door and forward assist
  • Weight: 7.6 oz.

20″ HBAR Chrome-Molybdenum Barrel


  • Profile: Heavy Barrel
  • Chamber: 5.56 NATO
  • Barrel Finish: Phosphate
  • Barrel Lining: Chrome
  • Barrel Steel: Chrome-Molybdenum
  • Barrel Thread: 1/2 x 28
  • Barrel Twist: 1:9
  • Feed Ramp: M4 Ramps
  • Front Site Base: A1-style (standard-height), with bayonet lug
  • Gas Block: .750 inch
  • Gas System: Rifle Length
  • Muzzle Device: A2-style Bird Cage
  • Weight: 2.9 lbs



  • Length: Rifle length
  • Lining: Aluminum Heat Shielded
  • Material: High Strength Polymer
  • Profile: Triangular A1, with Drainage Holes
  • Triangular end cap

Aero AR15 Lower Receiver, Gen 2 (Until I can get an A1-style lower)


  • Platform: AR15
  • Material: 7075-T6 forged aluminum
  • Finish: Mil-spec Type III Hard Anodized
  • Increased Magwell Flare, for easier insertion of magazines
  • Rear takedown pin detent hole threaded with a 4-40 set screw
  • Upper tension screw, nylon-tipped, tuned for a perfect fit with upper receiver
  • Weight: 8.35 ounces

Aero AR15 Lower Parts Kit


  • Standard Parts Kit


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